A script to exclude specific vertices from Shapekeys?
Found the answer on BA! So all I need to do is to

Select the Basis Shape Key, Tab into edit mode
Select the vertices you want to keep unchanged,
Hit Ctrl+V &gt;Propagate to Shapes.

And it will overwrite the vertices shapes in that particular area and thus will not change anymore. The downside is that it is going to apply it to all the shapes (my understanding) but that's ok for now.